diff --git a/src/math/FGParameterValue.h b/src/math/FGParameterValue.h
index 733608ab3..cbb2ab9a4 100644
--- a/src/math/FGParameterValue.h
+++ b/src/math/FGParameterValue.h
@@ -71,7 +71,7 @@ class FGParameterValue : public FGParameter
            << "The element <" << el->GetName()
            << "> must either contain a value number or a property name."
            << endl;
-      throw invalid_argument("Illegal argument");
+      throw invalid_argument("FGParameterValue: Illegal argument defining: " + el->GetName());
     }
 
     Construct(value, pm);